This invention relates to a novel locking device, and more particularly to a locking device adapted to enable to lock a driven member automatically at any position against a force applied thereon and yet to operate the driven member freely in accordance with motion of the drive member.
Hitherto, locking devices of this kind are broadly utilized in many industrial mechanisms such as in remote control mechanism of marine engine, side brake mechanism of automobiles and shutter mechanism, when it comes to necessitate to operate the driven member freely in accordance with motion of the drive member, and conversely to lock the driven member automatically at any position against continuous or occasional forces applied thereon without any influence upon the drive member. Furthermore, in the industrial mechanisms it sometimes becomes necessary to lock the driven shaft automatically against each of two opposite directional forces applied thereon. For example, with respect to the locking device used in the shutter mechanism, the locking device is not only to support it against the continuous force due to door weight, but also advantageously to support it against a manual force which might apply occasionally in opposite direction to said gravitative force to prevent the shutter from being opened without using key, or the like.
There are many other cases in which the direction of forces is altered occasionally or interchangeably.
A previous locking device, comprising pawls or clicks equipped on a driven shaft and a fixed locking member having many teeth which engage with the pawls, is lacking in the ability to lock the driven member at desired positions because the meshing between the pawls and the teeth are held at only some predetermined teeth positions. Besides, in such locking device, additional members are necessary to release the engagement to operate the driven member in accordance with motion of the drive member.
As for the locking device which locks the driven shaft automatically against each of two opposite directional forces applied thereon, a previous locking device which comprises a fixed sliding plate which is circular arc in shape, two locking members which have two locking elements respectively, which are pressed by resilient members in contrary gradient each other, a lever which makes the locking member slide along the sliding plate circularly, and a driven shaft which is connected to an arm member formed in other side of the lever, has a limited stroke length unavoidably because the sliding plate is circuler arc in shape. An uneven or chordal motion of the driven shaft due to circular motion of the arm member is another unavoidable withdrawback of such locking device.